MailFixture

wait_for_sms_otp

Block until an SMS with an extracted OTP/verification code arrives on the phone number, then return the code. The one-call answer to 'trigger SMS verification, read the code, type it in'. Returns {sms_id, best, candidates}.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "phone_number_id": "<phone_number_id>"
    },
    "name": "wait_for_sms_otp"
  }
}

Input Schema

Name	Required	Description
`match`	No	Filter: `from:term`, `to:term`, or `body:term`; a bare term matches the body.
`since`	No	Only consider messages received after this RFC 3339 timestamp. Omit to accept a message that already arrived.
`phone_number_id`	Yes	Phone number id (uuid) to watch.
`timeout_seconds`	No	Give up after this many seconds (default 45, max 60).

Schema Changelog

Changes observed during successful MCP inspections.

First observedJul 11, 2026

TDQS

A4.2/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description explicitly states blocking behavior and the extracted OTP return structure ({sms_id, best, candidates}). No annotations were provided, so the description carries the full burden, and it does so well without contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences delivering the core purpose and return format with zero extraneous information. Front-loaded with the blocking action and result.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the main behavior, blocking, and return fields. Given the complexity of waiting for a message with extraction, it is adequate. Minor omission: no mention of timeout behavior or error conditions, but those are handled in parameter schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Input schema has 100% coverage with detailed descriptions for all parameters. The description adds no new parameter-level insight beyond the schema, meeting the baseline expectation but not exceeding it.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool blocks until an SMS with an extracted OTP arrives and returns the code. It distinguishes from siblings like 'wait_for_sms' by emphasizing OTP extraction and being a one-call answer for verification flows.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides a concrete use case ('trigger SMS verification, read the code, type it in') and positions it as a convenient combined operation. However, it does not explicitly state when not to use it or compare to alternatives like 'get_otp'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All MailFixture tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?